Device for towing a very long tubular object

ABSTRACT

A device for towing very long tubular objects, comprises: pulling means capable of driving, by friction, the object in a towing direction, gripping means capable of exerting a load on the pulling means to keep the pulling means and the towed object in continuous contact; the gripping means being driven by a relative movement relative to the towed object in a direction opposite to the towing direction, driving means, capable of driving the pulling means and the gripping means in a coordinated manner to ensure a continuous and uniform pulling of the object, further comprising setting means, capable of adjusting the load exerted on the pulling means.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International patent applicationPCT/EP2015/065325, filed on Jul. 6, 2015, which claims priority toforeign French patent application No. FR 1401505, filed on Jul. 4, 2014,the disclosures of which are incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates to a device for towing very long elongateobjects. This device notably makes it possible to put to sea or elseraise and stow under deck a very long tubular object of relativelyflexible and brittle structure. Such objects that can notably be citedare submarine cables, pipes or even linear sonar antennas of “flute”type.

BACKGROUND

The handling of substantially tubular and very long objects is adifficult operation, particularly when the object handled has a flexibleand brittle structure comprising, for example, a succession ofrelatively brittle objects placed in a more flexible tubular sheath, oreven when the object exhibits irregularities of diameter over itslength. The problem arises in particular in the case of the sonarsystems, which surface vessels or submarine vessels are equipped with.The effectiveness of the detection of these systems is greatly dependenton the length of the antenna, and very long tubular antennas, forexample of flute type, are generally used. As is known, such linearantennas have a length of several hundred meters for a diameter of theorder of a few centimeters. In a mission, the antenna has to be put tosea, deployed to a sufficient length, then raised back on board thevessel at the end of the mission. This operation is difficult, both inthe case of a surface vessel, likely to be exposed to a choppy sea, andin the case of a submarine vessel for which the antenna and the towingdevice are submerged.

Various towing devices have attempted to resolve these difficulties.There is known, for example from the patent published under thereference U.S. Pat. No. 5,839,636, a device of caterpillar type ensuringthe towing of the antenna by means of two tracks facing one another andin contact with the antenna to be displaced. Also known from theapplicant is the towing device described in the patent applicationpublished under the reference FR 2858309. The principle of this knowndevice is recalled hereinbelow by means of FIG. 1. The general idea ofthe device is to decouple the loads exerted on the object to be towed byseparating means continuously ensuring the gripping of the object andmeans ensuring the pulling of the object.

As illustrated in FIG. 1, such a towing device comprises a frame 11supporting the following two means:

-   -   Pulling means, mainly consisting of two treads 12 arranged on        either side of and along the object to be towed 10. Each tread        12 is wound around two pulleys 13 and 14 fixed onto uprights        situated at each of the ends of the main frame.    -   Gripping means, consisting of a first flange 15 and of a second        flange 16, in the form of disks, linked to one another by        uprights 19. The flanges 15 and 16 are mounted to be        rotationally mobile about the longitudinal axis of the device        referenced X, by means of holding parts 17 and 18 via bearings        for example. The assembly forms a frame 114 that is rotationally        mobile relative to the frame 11. The central parts of the        flanges 15 and 16 and of the holding parts 17 and 18 are holed,        so as to be able to be passed through by the object 10 to be        towed and the treads 12.

The gripping means ensure the contact between the treads 12 and theobject to be towed 10 by means of a belt 110 helically wound around theobject to be towed and portions of the treads in contact with theobject. The winding is sufficiently tight to keep the object and thetreads in close contact. The ends of the belt are connected together toform a straight strand 111 which runs in the grooves of the opposingpulleys 112 and 113, fixed respectively onto each of the flanges 15 and16. The function of these pulleys 112, 113 is notably to ensure thetension of the belts fixed respectively to each of the flanges 15, 16.The assembly consisting of the flanges 15 and 16 and of the uprights 19forms a frame 114 that is rotationally mobile about the longitudinalaxis of the device.

To perform the towing of the object 10, the device also comprises meanssetting the pulling and gripping means in motion. These means comprise amain shaft 115 and a system of gears and of gearboxes 116 to whichsecondary shafts are coupled making it possible to rotate the pulleys 14which ensure the driving of the treads 12, and the pulley 16 whichdrives the frame 114 in rotation. In the exemplary embodiment, thepulley 16 is coupled via a belt 122 to another pulley 121 secured to theshaft 115.

To ensure the displacement of the object 10 in the direction indicatedby the arrow 118, the shaft 115 is actuated by means of a flywheel 117so that the rotation of the pulleys 14 drives the displacement of thetreads 12 in the direction indicated by the arrows 119. The displacementof the treads drives an identical displacement of the object 10. At thesame time, the rotation of the shaft 115 rotates the frame 114 in thedirection indicated by the arrow 120. This rotation drives the windingof the belts 110 on the side of the flange 15 and a simultaneousunwinding on the side of the flange 16. The effect of this dual actionis to provoke a relative displacement of the gripping means along theobject 10, in a direction opposite to the real displacement of theobject 10 and of the treads 12. Thus, the object 10 is able to progresslinearly while being kept closely in contact with the treads. Thedisplacement movement of the object is similar to the linear andcontinuous displacement of the free jaws of a vice along the worm screwwhich is used to tighten it, when the vice is tightened or untightened.Conversely, since the operation of the device is symmetrical byconstruction, the displacement of the object 10 in the oppositedirection will be able to be ensured by maneuvering the shaft 115 in theopposite direction by means of the flywheel 117. For the towing actionto be effectively feasible, the rotational movement of the frame drivesa relative displacement substantially equal to the displacement impartedon the object by the rotation of the treads 12. The coordination of thetwo movements can be ensured by mechanical means, for example a gearboxdevice mounted on the shaft 115.

SUMMARY OF THE INVENTION

This device presents many advantages compared to the prior devices, forexample of caterpillar type. In particular, the separation of thegripping and pulling functions into two means makes it possible todecouple the two loads exerted on the object, making it possible toexert an effective pulling force, without having to exert an excessive,and even damaging pressure on the object to be towed. Difficulties havehowever been observed that the present invention seeks to resolve.

The belt of the gripping means is a key component of the towing device.During the towing, the belt is wound and unwound by means of the mobileframe and of the pulleys rotating about the object to be towed. Toensure the gripping of the object, the belt is also stressed in tensioncontinuously. The belt, generally made of elastomer material, is exposedto the aggressivity of the marine environment, particularly in the caseof a submerged towing device. For these reasons, a rapid aging of thebelt has been observed. The replacement of the belt is complex andrequires difficult intervention on the device.

The invention aims to mitigate these difficulties encountered by thetowing devices of the prior art, by proposing a device that notablyallows for increased reliability and enhanced repairability.

To this end, the subject of the invention is a device for towing verylong tubular objects, comprising:

pulling means capable of driving, by friction, the object in a towingdirection,

gripping means capable of exerting a load on the pulling means to keepthe pulling means and the towed object in continuous contact, thegripping means being driven by a relative movement relative to the towedobject in a direction opposite to the towing direction,

driving means, capable of driving the pulling means and the grippingmeans in a coordinated manner to ensure a continuous and uniform pullingof the object.

The device further comprises setting means, capable of adjusting theload exerted by the gripping means on the pulling means.

Advantageously:

the pulling means comprise a tread coming into contact with the objectto be towed, produced in a material with strong adhesive power,

the gripping means comprise two main pulleys and a belt taut between thetwo main pulleys and helically wound around the object to be towed andthe tread, so as to exert a load on the tread to keep the tread incontinuous contact on the object to be towed,

the setting means comprise a return pulley that can be displacedrelative to the two main pulleys, so as to adjust the tension of thebelt, making it possible to adjust the load exerted by the tread on theobject to be towed.

Advantageously, the belt is elastically taut.

Advantageously:

the gripping means comprise a frame that is rotationally mobile aboutthe object pulling axis, formed by two flanges linked by longitudinaluprights and passed through by the object to be towed and the tread; afirst and a second of the two pulleys being fixed respectively onto afirst and a second of the two flanges,

the setting means comprise a mobile flange passed through by the objectto be towed and the tread, mounted between the first and the secondflange, the return pulley being fixed onto the mobile flange; the mobileflange being able to be displaced by translation between the first andthe second flanges so as to adjust the tension exerted on the belt; oneof the two main pulleys being a double pulley.

Advantageously, the gripping means comprise a frame that is rotationallymobile about the longitudinal axis of the object to be towed, the mainpulleys being translationally fixed along the longitudinal axis of theobject to be towed relative to the frame, the main pulleys being thefirst pulleys encountered by the belt at either end of its windingaround the object to be towed.

Advantageously, the return pulley can be displaced between a first and asecond determined position so as to make it possible to exert, on theobject to be towed, a load lying between a substantially zero minimumvalue and a predetermined maximum value.

Advantageously, the device is intended for towing an object exhibiting arelief over a portion of its length. The setting means are configuredsuch that the displacement of the relief during the towing drives thedisplacement of the return pulley to its first position, so as tosubstantially neutralize the load exerted by the tread on the object tobe towed.

Advantageously, the setting means comprise a linear actuator capable ofdisplacing the return pulley as a function of a setpoint.

Advantageously, the device comprises several first and second mainpulleys fixed respectively onto the first and the second flanges, thebelt being taut between the first and second main pulleys and helicallywound several times around the object to be towed and the tread.

Advantageously, the device comprises several belts and several first andsecond main pulleys fixed respectively onto the first and the secondflanges; each belt being associated with a first and a second mainpulley, taut between said first and second main pulleys, and helicallywound around the object to be towed and the tread.

Advantageously, the setting means comprise several return pulleys fixedonto the mobile flange.

Advantageously, the pulling means comprise a spring mechanism configuredto tighten the tread so as to adapt to a variation of diameter of theobject to be towed.

Advantageously, the pulling means comprise at least one tread having acircular arc form, so as to closely follow the form of the object to betowed over a portion of its circumference.

Advantageously, the pulling means comprise several treads coming intocontact with the object to be towed, produced in a material with strongadhesive power.

Advantageously, the device comprises a brake capable of slowing down thegripping means or the pulling means.

Advantageously, the device comprises means for measuring the movement ofthe object towed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and other advantages will becomeapparent on reading the detailed description of embodiments given by wayof example in the following figures.

FIG. 1, already presented, represents a device for towing an objectaccording to the known art, comprising pulling means and gripping means,

FIG. 2 illustrates the principle of a towing device comprising means forsetting the load exerted by the gripping means on the pulling means,

FIGS. 3a and 3b represent a first example of a towing device comprisingmeans for setting the gripping load, respectively in a disengagedconfiguration and an engaged configuration,

FIG. 4 represents, by exploded view, a second example of a towing devicecomprising several modular subassemblies.

In the interests of clarity, the same elements will bear the samereferences in the different figures.

DETAILED DESCRIPTION

The present invention relates to improvements to the towing devicedescribed in the preamble of this application with reference to thepatent application FR 2858309. The towing device according to theinvention comprises a certain number of components in common with thisprior art device. Hereinbelow, the structural or functional definitionof the components in common with the prior art device is notsystematically repeated, but is deduced directly from the description ofthis known device. The device according to the invention is ofparticular use for towing a very long linear antenna, which the sonarsystems that are for example embarked on submarines are equipped with.Obviously, this particular application is not limited to the inventionwhich more broadly covers a device suitable for handling substantiallytubular and very long objects. The device can be implemented in variousfields. The device can be fully submerged in a marine environment in theparticular case of a submarine application, or exposed to the ambientair and to the weather in the case of a stationary device on land oreven in the case of an antenna pulled from a surface vessel.

In order to limit or slow down the wear of the gripping means, theinvention relates firstly to a device comprising means making itpossible to adjust the load exerted by the gripping means on the objectpulling means.

FIG. 2 illustrates the principle of a towing device comprising settingmeans, or setting subassembly for making it possible to adjust, duringthe towing of the object, the load exerted on the pulling means. Aspreviously, the towing device comprises:

pulling means, or tractor or pulling subassembly, capable of driving, byfriction, the object 10 in a towing direction 118,

gripping means, or gripper or gripping subassembly, capable of exertinga load on the pulling means to keep the pulling means and the towedobject continuously in contact; the gripping means being driven in arelative motion in relation to the towed object in a direction oppositeto the towing direction,

driving means, or driving device, capable of driving the pulling meansand the gripping means in a coordinated manner to ensure a continuousand uniform pulling of the object.

In a preferred embodiment, the pulling means comprise at least one tread12 coming into contact with the object to be towed, and produced in amaterial with strong adhesive power. The tread 12 is taut between twopulleys 13 and 14 and driven in motion by the driving means (notrepresented). The adhesion of the tread makes it possible to drive theobject to be towed 10 in its movement, by friction. The pulling meansand the object to be towed are kept continuously in contact at leastover a section of the object. The surface of the tread 12 coming intocontact with the surface of the object 10 is preferably rough in orderto ensure a better pulling adhesion.

A towing device is envisaged in which the pulling means comprise asingle tread, or preferentially a plurality of treads. A device isnotably envisaged that comprises two treads arranged facing one anotherand on either side of the object to be towed, as represented in FIG. 2.A towing device is also envisaged that comprises more than two treads,for example three or four treads, distributed angularly, in starfashion, around the object to be towed.

In a preferred embodiment, the gripping means comprise at least one belt110 taut between two pulleys 112 and 113, called main pulleys, andhelically wound around the object to be towed 10 and the tread 12. Thebelt 100 forms a straight strand 100 which runs in the grooves of theopposing pulleys 112 and 113. If the pulling means comprise severaltreads 12, the belt is helically wound around the object 10 and each ofthe treads. Configured thus, the tension of the belt 110 exerts a loadon the tread or treads, making it possible to keep the pulling means andthe object to be towed in continuous contact.

Advantageously, the belt is produced in an elastic material.Advantageously, the belt is elastically taut. The belt 110 isadvantageously elastically taut between the two main pulleys 112, 113and helically wound around the object to be towed so as to exert theload on the tread to keep the tread continuously in contact on theobject to be towed. Advantageously, the belt 110 is elastically tautover its entire length. Thus, the belt automatically adapts to a changeof diameter of the object to be towed. The adaptation of the diameter ofthe cable does not require the provision of any dedicated return device.

The gripping means comprise a frame 114 that is rotationally mobileabout the pulling axis X of the object. The mobile frame 114 is in theform of two flanges 15 and 16 linked by longitudinal uprights 19 andpassed through by the object to be towed and the tread or treads 12. Afirst main pulley 112 is fixed onto a first flange 15. A second mainpulley 113 is fixed onto a second flange 16.

According to a principle similar to that described in the preamble withregard to FIG. 1, the decoupling of the pulling function—produced bymeans of the treads 12, and of the gripping function—produced by meansof the belt 110 helically wound around the treads, is obtained bydriving the two means in a coordinated manner. The driving means (notrepresented in FIG. 2) ensure, on the one hand, the displacement of thetread 12, for example by driving one of the pulleys 13 or 14 inrotation; the adhesion of the tread driving the displacement of theobject to be towed in its movement, by friction. The driving means alsoensure the winding and the unwinding of the belt 110 by driving theframe 114 in rotation. The object 10 is then driven in translation alongthe axis X, while being kept closely in contact with the treads.

The driving means are configured to ensure a coordinated driving of thepulling means and of the gripping means. For example, the driving meanscomprise an actuator, such as an electric motor, a heat engine or ahydraulic motor, and a synchronization mechanism capable of converting arotational movement generated by the actuator into two coordinatedmovements making it possible to drive the pulling means, for example bydriving the pulley 14 in rotation, and the gripping means, for exampleby driving the mobile frame 114 in rotation. The driving means cancomprise a gearbox device mounted on a main shaft driven by a rotaryactuator, comprising, for example, a gear and gearbox system 116 towhich are coupled two secondary shafts making it possible to rotate thepulleys 14 which ensure the driving of the treads 12, and the pulley 16which drives the frame 114 in rotation. Other forms of driving means canalso be envisaged without departing from the scope of the invention. Forexample, the pulling and gripping means can be driven by independentdedicated actuators and a control device ensuring the synchronizationbetween the two actuators.

Gripping means comprising several belts are also envisaged. The beltsare advantageously helically wound around the object to be towed and inan entangled manner along the towing direction. Each of the belts can betaut between two main pulleys linked respectively to the first andsecond flanges 15 and 16. Each belt ensures that the pulling means areheld on the object to be towed. The rotation of the mobile frame drivesthe winding and the unwinding of each of the belts simultaneously. Themounting of each of the belts is then advantageously similar andidentical to that which will be described hereinbelow, notably withregard to the mounting of the belt with the main pulleys and the returnpulley.

The device according to the invention therefore comprises two distinctmeans or subassemblies for ensuring the pulling and gripping functions.The pulling means are driven by a translational movement along the axisof the object whereas the gripping means are driven by a rotationalmovement about the same axis. The separation of the means has theadvantage of ensuring the decoupling of the loads exerted on the objectto be towed. That makes it possible to set the force driving the objectto be towed by acting on two independent parameters, namely the treaddriving torque and the tension of the belt.

These two means exerting distinct functions cooperate to ensure acontinuous pulling of the object to be towed and a good distribution ofthe stresses over its surface. The device as a whole has a fixedposition.

According to an aspect of the invention, the towing device alsocomprises setting means configured to be able to adjust the load exertedon the pulling means. In the example represented in FIG. 2, the settingmeans comprise a return pulley 30, on which the belt 110 is mounted. Thereturn pulley 30 can be displaced relative to the two main pulleys 112and 113, so as to adjust the tension of the belt 110, making it possibleto adjust the load exerted by the tread on the object to be towed.

Preferentially, the main pulleys 112, 113 are fixed in translation alongthe longitudinal axis X of the object to be towed relative to the framewhich is rotationally mobile about the axis of the object to be towed.In other words, the main pulleys are not translationally mobile alongthe longitudinal axis of the object to be towed 10 relative to the frame114. The main pulleys 112, 113 are the first pulleys encountered by thebelt 110 at either end of its winding around the object to be towed 10,that is to say on leaving its winding around the object to be towed ateither end of said winding. The return pulley 30 is encountered afterthe main pulleys on leaving the winding. The return pulley 30 istranslationally mobile relative to the main pulleys 112, 113 along thelongitudinal axis of the object to be towed 10.

Consequently, when the return pulley is translated along thelongitudinal axis relative to the main pulleys, the pitch of the helix,the angle of the helix and the length of the helix formed by the belt110 along the longitudinal axis of the object to be towed remainunchanged. That makes it possible to well control the load exerted onthe object to be towed by the pulling means (and notably by the tread(s)12) because it depends only on the tension of the belt and on limitingthe risks of flexing of the object to be towed, by virtue of the tensionof the pulling means. Moreover, because of retention of the helix pitchand angle formed by the belt 110, the risk of overlapping of the turnsof the helix in the translation of the return pulley is limited whichlimits the risks of jamming of the object to be towed. Now, once theobject is jammed because of the overlapping of the turns, it isnecessary to dismantle and remount the belt to be able to once again usethe towing device.

Preferentially, the setting means comprise a mobile flange 31, passedthrough by the object to be towed 10 and the tread or treads 12, mountedbetween the two flanges 15 and 16. The return pulley 30 is fixed ontothe mobile flange 31. The mobile flange 31 can be displaced intranslation along the axis X, as represented by the arrow 300, betweenthe first and the second flanges 15 and 16, so as to adjust the tensionof the belt 110. For that, the mobile flange 31 comprises openingspassed through by the longitudinal uprights 19. The openings of themobile flange can be configured so as to ensure the translationalguiding of the flange relative to the longitudinal uprights.

The mounting of the belt 110 represented in FIG. 2 is similar to that oftackle generally implemented to reduce the load necessary to bring twosets of pulleys closer together. In this case, the tackle-mounting ofthe belt by means of a return pulley, otherwise known as tackle block,that can be displaced relative to two fixed pulleys, advantageouslymakes it possible to modify the tension of the belt. In the examplerepresented in FIG. 2, the belt is taut between a pulley 112, a returnpulley 30 and a double pulley 113 with two different diameters. Thetackle-mounting can implement double pulleys of distinct diameters, asrepresented in FIG. 2, or double pulleys of the same diameters, asrepresented in the subsequent figures. Various types of mounting of thebelt around the main pulleys and the return pulleys are possible withoutdeparting from the scope of the invention.

In a preferred implementation, the setting means are configured to makeit possible to displace the return pulley between a first and a secondposition, determined so as to exert, on the object to be towed, a loadlying between a minimum value close to zero and a predetermined maximumvalue. In the first position, the belt is very weakly taut around theobject to be towed. The device is in a so-called disengaged position.The tension of the belt could have been zero in the first position.Advantageously, a low tension is retained in this position so as toavoid having the belt escape from the pulleys. In the first position,the tension of the belt is such that the towing device does not make itpossible to tow the object to be towed. In other words, the minimumvalue of the load exerted on the object to be towed, by the belt 110 andthe tread(s) 12, does not make it possible to tow the object to be towedby the displacement of the tread(s). The friction load is insufficientto ensure the towing. In the so-called engaged second position, amaximum tension is imposed on the belt. The load exerted by the belt onthe tread or treads is maximal. This load makes it possible to tow theobject to be towed. Advantageously, the value of the minimum load liesbetween 5 Newtons and 100 Newtons.

The towing device thus provided with the setting means advantageouslymakes it possible to adapt the tension exerted on the belt. The settingcan be carried out during the towing, both to increase or reduce thetension of the belt and therefore the towing load. The towing device canbe configured to make it possible to disengage the object to be towed,by exerting a gripping load close to zero on the object.

The setting means advantageously make it possible to limit the aging ofthe belt, generally made of elastomer material. Contrary to the priorart devices, it becomes possible to adapt the tension of the belt ateach instant according to the needs of the mission. In practice, itbecomes possible to impose a tension on the belt only during a towingoperation. For an application to a sonar system, the tension of the beltcan be relaxed as soon as the deployment or the removal of the antennais completed.

Obviously, the benefits of the prior art device are retained. The towingdevice according to the invention thus makes it possible to ensure acontinuous towing movement, avoiding having the towed object undergojerks that could damage it. The movement is also reversible and can beused to put the object into the water or remove it. The device accordingto the invention can also advantageously be adapted to towing an objectwhose section is not constant or even objects made up of rigid portionsand more flexible portions. It can finally operate automatically andthus offers the advantage of limiting the need for human intervention insometimes fairly perilous conditions.

FIGS. 3a and 3b represent a first example of a towing device comprisingadjustable gripping means, respectively in a disengaged configurationand an engaged configuration.

This example of towing device 50 applies the principle described aboveby means of FIG. 2. Thus, the device 50 comprises:

pulling means capable of driving the object to be towed by friction,

gripping means capable of exerting a load on the pulling means keepingthe pulling means and the towed object in contact,

driving means, capable of driving the pulling means and the grippingmeans in a coordinated manner.

The pulling means comprise two treads 12 with strong adhesive power,taut between two pulleys 13 and 14 that can be driven in rotation by thedriving means (not represented). The gripping means comprise a mobileframe 114 formed by two flanges 15 and 16 linked by longitudinaluprights 19. The flanges 15 and 16 are in the form of a holed disk, andare passed through by the object to be towed (not represented) and thetwo treads. The gripping means also comprise a belt 110 helically wound,between the flanges 15 and 16, around the object to be towed and the twotreads. The frame 114 is rotationally mobile about the pulling axis X.It can be driven by the driving means via two toothed wheels 15 a and 16a mounted at the periphery of the two flanges 15 and 16.

The device 50 also comprises setting means capable of adjusting, duringthe towing of the object, the load exerted on the pulling means. Aspreviously, the setting means comprise a return pulley 30 fixed onto aflange 31 that is translationally mobile between the two flanges 15 and16. In FIG. 3a , the mobile flange 31 is in a first position imposing alow tension on the belt, the load exerted between the treads and theobject to be towed is close to zero as has been described previously.The device is in disengaged configuration. In FIG. 3b , the mobileflange 31 is in a second position imposing a high tension on the belt,the loading exerted between the treads and the object to be towed ismaximal. The device is in an engaged configuration.

The invention envisages switching over between the two positions bymeans of a dedicated actuator, such as, for example, an electric orhydraulic linear actuator, capable of displacing the mobile flange.Implementing a disengaging mechanism linked to the displacement of theobject to be towed is also envisaged. Thus, the setting means can beconfigured so that a relief on the surface of the object to be towed,such as, for example, an end-of-travel stop mechanically drives, by thedisplacement of the towed object, the displacement of the return pulleyto its disengaged position, so as to substantially neutralize the loadexerted by the tread on the object.

Note also that the device 50 represented in FIGS. 3a and 3b isdistinguished from the devices already described by the architecture ofthe gripping means and of the setting means. In particular, the grippingmeans comprise several main pulleys 112 and 113 on each of the flanges15 and 16. In the example represented, the belt 110 is taut between sixpulleys 112 fixed onto the flange 15 and six pulleys 113 fixed onto theflange 16. The belt is helically wound around the object to be towed andthe treads in six successive passes. This type of mounting with severalentangled helixes advantageously makes it possible to balance thetension exerted on the belt and to angularly distribute the load exertedon the treads. It allows for a greater variation of the tension of thebelt, that is to say of the length of the belt.

The setting means also comprise several return pulleys 30 fixed onto themobile flange 31. In the example represented, six return pulleys arefixed onto the mobile flange 31, and cooperate with the six single 112and double 113 main pulleys of the flanges 15 and 16. The translationaldisplacement of the mobile flange 31 makes it possible to adjust thetension of the belt 110 in a balanced manner. The load exerted on thetreads is angularly distributed uniformly.

The invention also envisages implementing pulling means comprising oneor more treads 12 having a circular arc form, so as to closely followthe form of the object to be towed over a portion of its circumference.

According to another aspect of the invention, the device canadvantageously comprise means for adjusting the tension of the treadswound between the pulleys 13 and 14. As represented in FIGS. 3a and 3b ,the pulleys 13 are fixed onto a flange 202 that can slide along thelongitudinal axis X relative to the frame 11. The flange 202 is linkedto the frame 11 via a set of springs 201 tending to separate the pulleys13 and the frame 114 from one another, so as to strain the tread 12 intension. In other words, the pulling means are provided with a springmechanism 201 configured to tauten the tread or treads. Thisconfiguration advantageously makes it possible to adapt to variations ofdiameter of the object to be towed.

The difficulties encountered by the prior art devices in performingmaintenance operations on the towing device were indicated in thepreamble to the present application. In particular, the periodicreplacement of the elastomer belt of the gripping means is an operationthat is difficult to perform. The invention therefore seeks tofacilitate maintenance or repair interventions on the device.

FIG. 4 represents, in an exploded view, a second example of a towingdevice comprising several modular subassemblies. In this second example,the device 60 comprises a casing 61 intended to be mounted for exampleon a marine vessel, and a removable assembly 62. The removable assemblysimilar to the device described previously by FIGS. 3a and 3b . Itnotably comprises pulling means 63 and gripping means 64. It can alsocomprise means for setting the load exerted on the pulling means. It ishowever clearly understood that the principle of a modular towingdevice, allowing for improved repairability, is also applicable in theabsence of these setting means.

The embodiments previously described for the pulling 63, gripping 64 orsetting means are envisaged for this second exemplary device. Thedetailed definition thereof is not repeated systematically hereinbelow.

As represented in FIG. 4, the casing 61 comprises a bottom part 61 a anda top part 61 b that are removable, between which the removable assembly62 can be mounted. The casing 61 further comprises an actuator 66, suchas a heat engine, an electric motor or a hydraulic motor, and asynchronization mechanism 67 driven by the actuator 66.

The synchronization mechanism 67 is removably linked to the pulling 63and gripping 64 means. The synchronization mechanism 67 is configured todrive the movement of the pulling means 63 and the gripping means 64 ina coordinated manner to ensure a continuous and uniform pulling of theobject.

The pulling means comprise at least one pulley 14 and one tread 12coming into contact with the object to be towed and that can be drivenin movement by rotation of the pulley 14. The synchronization mechanism67 comprises a shaft 70, configured to rotationally drive the pulley 14of the pulling means. The pulley 14 and the shaft 70 can be coupledremovably by means of two dog clutches 71 a and 71 b, securedrespectively to the pulley 14 and the shaft 70. The two dog clutchesform a coupling subassembly or a coupling device. Other coupling meansor coupling subassemblies are also envisaged, in particular a frictioncoupling. In FIG. 4, the pulling means comprise two treads driven bymeans of two pulleys. The synchronization means logically comprise twoshafts 70 capable of driving the two treads, and coupled with the twopulleys 14 removably by means of two dog clutch devices.

As previously described, the gripping means comprise a frame that isrotationally mobile about the pulling axis of the object, formed by afirst and a second flange 15 and 16 linked by longitudinal uprights andpassed through by the object to be towed and the tread. Each of thefirst and second flanges 15 and 16 comprise a toothed wheel,respectively referenced 15 a and 16 a, mounted at the periphery of eachof the flanges. The rotation of the toothed wheels rotationally drivesthe mobile frame, by winding and unwinding the belt respectively on theside of the first and of the second flange. The synchronizationmechanism 67 comprises a first pinion 75 a and a second pinion 76 aconfigured to cooperate respectively with the first and the secondtoothed wheels 15 a and 16 a so as to rotationally drive the mobileframe. Ensuring the rotational driving of the mobile frame by means of asingle pinion and toothed wheel assembly is also envisaged. Moreover,the toothed wheel or wheels can be mounted at the periphery of theflanges, or more generally be secured to the mobile frame.

In the case where the removable assembly 62 comprises means for settingthe load exerted on the pulling means, by displacement of a returnpulley relative to the two main pulleys, the casing can advantageouslycomprise a second actuator, for example a linear or hydraulic actuator,removably linked to the setting means and configured to make it possibleto displace the return pulley.

This configuration of a removable towing device is particularlyadvantageous. In case of failure of the pulling or gripping means, or ina periodic maintenance operation, the removable assembly 62 can beseparated from the casing, and transported to a workshop to facilitatethe intervention of an operator. The removable assembly can also bereplaced by a second assembly to ensure a continuity of mission duringmaintenance on the removable assembly. The structural elements and themore reliable components (motor, synchronization mechanism) remainpermanently fixed to the vessel.

Advantageously, the pulling means and the gripping means of theremovable assembly can be linked to the driving means by a singletranslational movement of the removable assembly relative to the casingin a plane at right angles to the towing direction. By positioning thetowing direction of the device on a horizontal axis, the removableassembly can be mounted in and dismantled from the casing by a verticaldisplacement relative to the casing, simultaneously coupling the toothedwheels with the pinions, and the pulley with the shaft. To this end, thedevice is advantageously provided with lifting means or a lifting deviceconfigured to make it possible to displace the removable assemblyrelative to the casing in a maintenance operation.

The present invention also envisages providing the towing device with abrake capable of slowing down the gripping means or the pulling means.The brake can be configured to act at the output of the motor or on therotationally mobile frame.

To improve the capacity to drive the towing device, it is also envisagedto implement measurement means comprising at least one sensor making itpossible to measure the movement of the towed object, for example asensor of displacement or a sensor of speed of the towed object.

The invention claimed is:
 1. A device for towing very long tubularobjects comprising: pulling means capable of driving, by friction, theobject in a towing direction, gripping means capable of exerting a loadon the pulling means to keep the pulling means and the towed object incontinuous contact; the gripping means being driven by a relativemovement relative to the towed object in a direction opposite to thetowing direction, driving means capable of driving the pulling means andthe gripping means in a coordinated manner to ensure a continuous anduniform pulling of the object, further comprising setting means, capableof adjusting the load exerted by the gripping means on the pullingmeans, wherein: the pulling means comprise a tread coming into contactwith the object to be towed, produced in a material with strong adhesivepower; the gripping means comprise two main pulleys and a belt tautbetween the two main pulleys and helically wound around the object to betowed and the tread, so as to exert a load on the tread to keep thetread in continuous contact on the object to be towed; the setting meanscomprise a return pulley guiding the belt and being able to be displacedrelative to the two main pulleys, so as to adjust the tension of thebelt, making it possible to adjust the load exerted by the tread on theobject to be towed; the gripping means comprise a frame that isrotationally mobile about the object pulling axis, formed by two flangeslinked by longitudinal uprights and passed through by the object to betowed and the tread, a first and a second of the two pulleys being fixedrespectively onto a first flange and a second flange of the two flanges;and the setting means comprise a mobile flange passed through by theobject to be towed and the tread, mounted between the first and thesecond flange, the return pulley being fixed onto the mobile flange; themobile flange being able to be displaced by translation between thefirst and the second flanges so as to adjust the tension exerted on thebelt.
 2. The towing device as claimed in claim 1, wherein the belt isproduced in an elastomer material.
 3. The towing device as claimed inclaim 1, wherein the belt is elastically taut.
 4. The towing device asclaimed in claim 1, wherein the gripping means comprise a frame that isrotationally mobile about the longitudinal axis of the object to betowed, the main pulleys being translationally fixed along thelongitudinal axis of the object to be towed relative to the frame, themain pulleys being the first pulleys encountered by the belt at eitherend of the belt winding around the object to be towed.
 5. The device asclaimed in claim 1, wherein the return pulley can be displaced between afirst and a second determined position so as to make it possible toexert on the object to be towed a load lying between a minimum valueclose to zero and a predetermined maximum value.
 6. The device asclaimed in claim 5, intended for towing an object exhibiting a reliefover a portion of a length of the object, and of which the setting meansare configured such that the displacement of the relief during thetowing drives the displacement of the return pulley to a first position,so as to substantially neutralize the load exerted by the tread on theobject to be towed.
 7. The device as claimed in claim 1, comprisingseveral first and second main pulleys fixed respectively onto the firstflange and the second flange; the belt being taut between the first andsecond main pulleys and helically wound several times around the objectto be towed and the tread.
 8. The device as claimed in claim 1, whereinthe gripping means comprise several belts and several first and secondmain pulleys fixed respectively onto the first flange and the secondflange; each belt being associated with a first and a second main pulleyand taut between said first and second main pulleys and helically woundaround the object to be towed and the tread.
 9. The device as claimed inclaim 1, wherein the setting means comprise several return pulleys fixedonto the mobile flange.
 10. The device as claimed in claim 1, whereinthe pulling means comprise a spring mechanism configured to tighten thetread so as to adapt to a variation of diameter of the object to betowed.
 11. The device as claimed in claim 1, wherein the pulling meanscomprise a plurality of treads coming into contact with the object to betowed, produced in a material with strong adhesive power.
 12. The deviceas claimed in claim 1, comprising at least one sensor for measuring themovement of the towed object.
 13. A device for towing very long tubularobjects comprising: pulling means capable of driving, by friction, theobject in a towing direction, gripping means capable of exerting a loadon the pulling means to keep the pulling means and the towed object incontinuous contact; the gripping means being driven by a relativemovement relative to the towed object in a direction opposite to thetowing direction, driving means capable of driving the pulling means andthe gripping means in a coordinated manner to ensure a continuous anduniform pulling of the object, further comprising setting means, capableof adjusting the load exerted by the gripping means on the pullingmeans, wherein: the pulling means comprise a tread coming into contactwith the object to be towed, produced in a material with strong adhesivepower; the gripping means comprise two main pulleys and a belt tautbetween the two main pulleys and helically wound around the object to betowed and the tread, so as to exert a load on the tread to keep thetread in continuous contact on the object to be towed; the setting meanscomprise a return pulley guiding the belt and being able to be displacedrelative to the two main pulleys, so as to adjust the tension of thebelt, making it possible to adjust the load exerted by the tread on theobject to be towed; and the return pulley can be displaced between afirst and a second determined position so as to make it possible toexert on the object to be towed a load lying between a minimum valueclose to zero and a predetermined maximum value.
 14. The device asclaimed in claim 13, wherein the device is configured to tow an objectexhibiting a relief over a portion of a length of the object, and ofwhich the setting means are configured such that the displacement of therelief during the towing drives the displacement of the return pulley toa first position, so as to substantially neutralize the load exerted bythe tread on the object to be towed.
 15. The device as claimed in claim14, wherein in the first position, the load is insufficient to ensuretowing of the object to be towed.
 16. A device for towing very longtubular objects comprising: pulling means capable of driving, byfriction, the object in a towing direction, gripping means capable ofexerting a load on the pulling means to keep the pulling means and thetowed object in continuous contact; the gripping means being driven by arelative movement relative to the towed object in a direction oppositeto the towing direction, driving means capable of driving the pullingmeans and the gripping means in a coordinated manner to ensure acontinuous and uniform pulling of the object, further comprising settingmeans, capable of adjusting the load exerted by the gripping means onthe pulling means, wherein: the pulling means comprise a tread cominginto contact with the object to be towed, produced in a material withstrong adhesive power; the gripping means comprise two main pulleys anda belt taut between the two main pulleys and helically wound around theobject to be towed and the tread, so as to exert a load on the tread tokeep the tread in continuous contact on the object to be towed; thesetting means comprise a return pulley guiding the belt and being ableto be displaced relative to the two main pulleys, so as to adjust thetension of the belt, making it possible to adjust the load exerted bythe tread on the object to be towed; the return pulley can be displacedbetween a first and a second determined position so as to make itpossible to exert on the object to be towed a load lying between aminimum value close to zero and a predetermined maximum value; and thedevice is configured to tow an object exhibiting a relief over a portionof a length of the object, and of which the setting means are configuredsuch that the displacement of the relief during the towing drives thedisplacement of the return pulley, so as to substantially neutralize theload exerted by the tread on the object to be towed.